My 2004 XJ8 refused to start. The starter turns over fine, but the engine doesn't kick in. I connected my OBD II reader to the car and all it would say was NO LINK. That's never happened before.

I tried the reader in a Toyota Camry and it worked fine, but only in the "all power on" ignition position.

(I warmed up the garage, recharged the battery to full, swapped a relay that can cause starting failure, and changed my engine air filter (it needed changing anyway), but none of that helped. Ordered a K&N fuel filter; haven't gotten it yet.)

 

Well not really enough information and the possibilities are many but since your message is no link, I would personally do a hard reset - disconnect the battery, hold the Pos and Neg cables for a minute. Then reconnect the battery and see if you get a signal.

Next place I would check is the ECU harness connection.

Start there. Others will weigh in.

 

I'm not understanding this. A scanner will only read data in the ignition on or with engine running. Are you saying this about your Toyota or Jaguar?

 

Have you checked the fuse for the diagnostic connector?

 

Hi Xeno,

Just to elaborate on Sean's questions, did you have the Jaguar's key turned to Position II (ON) when you attempted to use your OBDII scanner? The scanner will not work with the key in Position I or out of the ignition lock.

In your Toyota, the scanner should work with the key in Position II with or without the engine running. Your Jag should work that way too once you get it running again.

One possibility is that even though you recharged the battery, its voltage while cranking is sagging too low. If the voltage drops to around 10.5 volts while cranking the ECM will not trigger the ignition to fire. Most voltmeters do not react quickly enough to measure the true voltage sag.

Out of curiosity, which relay did you swap?

The reset Sean recommends will get your scanner working, but any stored fault codes may be cleared from the memory....

The next steps would be to confirm that you have good spark and fuel pressure at the fuel rail.

Cheers,

Don

 

So two options here I think as I'm always suspicious when someone says they just put a full charge on it. Why wasn't it fully charged already?
One, pull the battery and have it load tested at your local auto parts store. To Don's point, it may be enough voltage to crank but not enough to start.

Option 2- put your voltmeter in the posts. Have someone crank the engine and measure the drop (load). If it's below 10.5, consider a new battery.

I'm also curious as to the relay swap. Which one and what compelled you to do it?

 

I didn't even know about it. Good idea, but I just checked it and it's fine.

 

It will read from the Toyota but not from the Jaguar. I don't know what people mean by "ignition on" when the igniter isn't on. The electrical power system has 4 positions: off, a few lights on, all the lights on, and the igniter on.

I tried the scanner in the Jaguar with the key in all positions. The Toyota has no ignition key. It has a button. Pushing it once turns some lights on. Pushing it again turns more lights on. Holding it down turns the igniter on.

Possible, but this is a ~1000 CCA battery that I bought 1 year ago and have driven maybe 4000 miles.

There are 2 small relays in the engine fuse box which are labelled with the same part number. One is the fuel pump relay. I swapped them.

I don't know how to do that, or where the fuel rails are. I'll check YouTube. Thanks!

I just checked all the fuses that sounded like they had anything to do with the ignition or the fuel pump, but they were all good. (I wish the relays had holes in their heads so we could test them without removing them.)

My immediate plan is to put in a new fuel filter, which I need to do anyway (86K mi and never changed AFAIK) and see what happens.

 

I usually don't drive the car far enough to recharge it enough to make up for starting it. I live in a small town, and most of my trips are under a mile. Also, it may have been fully charged. I didn't check until I'd tried to start the car maybe 8 times. The car had previously given me no problems at all starting.

The fuel pump relay. Because it said "fuel pump". I don't really know what it does.

 

I never disconnected the battery. I used a different OBD and got a readout of P1111, which is useless (OBD checks complete since last memory clear).
I cleared that, then immediately got a P1000 (System readiness test not complete).

Then I put the first OBD in, and it worked (giving a P1000).

I'm starting a new post for the "won't start" problem, but the "no link" problem is solved, I guess.

 

On the contrary having P1111 and no other codes is very important. By clearing it, you got P1000 and will have to drive the car long enough for all the monitors to do their systems check at which point P1111 will reappear if all is well.

Never delete P1111 if that's the only code.

Sounds like your no start problem lies elsewhere. Are you sure the engine is not flooded with fuel? This is very common with engines that never get chance to warm up properly, even worse in winter.

Hold the gas pedal to the floor while you crank and don't let up till the engine starts to fire.

 

Huh. I had let the car sit for a full day before trying to start it again, in case it was flooded, but that hadn't helped. I did what you said just now, and it started, and I went for a drive. No check engine light, no codes. And I'd been getting ready to call a tow truck. Thanks!

The engine block still makes that same whining noise when I turn the ignition to the 3rd position. Is that normal? Most people probably wouldn't hear it without opening the hood.

 

Glad it worked!